Digital image capturing devices include cameras, portable handheld electronic devices, and electronic devices. Often these digital image capturing devices are highly compact. They may be integrated as part of a multifunction device such as a personal digital assistant (PDA) or mobile telephone.
A digital imaging subsystem that includes a lens and an image sensor may be provided as a single sub-assembly for building the device so that all components requiring high precision optical alignment are pre-assembled. This permits economy of scale in the production of the digital imaging subsystem, which may used in many different devices. This also lowers the cost of producing the device that includes the digital imaging subsystem because the assembly process for the device does not have to include the procedures for providing optical alignment of the digital imaging components.
As the quality of digital images that can be obtained with highly compact devices increases, there is increasing demand for sophisticated features previously found only in high-end digital cameras, such as digital single lens reflex (DSLR) cameras. Cameras providing features such as supplementary lenses and filters, optical zoom, optical image stabilization, and other features useful in capturing high quality images have typically been much larger than multifunction devices that include a camera.
High-end digital cameras may be constructed with a camera body that provides a mechanical receptacle for receiving a variety of lenses and aligning them precisely with the image sensor in the camera body. These replaceable lenses and non-replaceable lenses on other digital cameras may provide a lens and filter mount at the front of the lens that can receive a lens or filter that is connected directly to the lens, thus ensuring a precise optical alignment with the lens.
The use of a pre-assembled digital imaging subsystem in a highly compact device precludes the use of replaceable lenses. Further, the lenses in a pre-assembled digital imaging subsystem are much smaller than those found in a dedicated digital camera and they do not provide a mount for filters or additional lenses. The digital imaging subsystem is typically enclosed within the case of the device to protect the digital imaging subsystem. The enclosure generally prevents direct access to the lens of the digital imaging subsystem for the purpose of providing any sort of supplementary optics, especially if the supplementary optics must be precisely aligned with the image sensor. Thus it is necessary to offer a number of different models of a compact device if a range of camera features is to be offered. Further, the camera features of a model are limited to what can be provided with a single optical configuration.
It would be desirable to provide a structure for a compact device that allows the end user to reconfigure the optical arrangement of the device while retaining the benefits of assembling the device using a pre-assembled digital imaging subsystem.